1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate by a liquid. Examples of substrates to be processed include semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, substrates for solar cells, etc.
2. Description of the Related Art
In substrate processing by a single substrate processing type substrate processing apparatus that processes a substrate one by one, for example, a chemical liquid is supplied to the substrate that is held substantially horizontally by a spin chuck. Thereafter, a rinse liquid is supplied to the substrate and the chemical liquid on the substrate is thereby replaced by the rinse liquid. Thereafter, a spin drying step is performed to remove the rinse liquid on the substrate.
As shown in FIG. 22, when a fine pattern is formed on a front surface of the substrate, it may not be possible to eliminate the rinse liquid, which has entered into an interior of the pattern, by the spin drying step and this may cause drying failure to occur. A liquid surface (an interface of air and liquid) of the rinse liquid that has entered into the interior of the pattern is formed inside the pattern and therefore surface tension of the liquid acts at positions of contact of the liquid surface and the pattern. When the surface tension is high, pattern collapse occurs readily. Water, which is a typical rinse liquid, is high in surface tension and therefore pattern collapse in the spin drying step cannot be neglected.
Therefore, in Japanese Patent Application Publication No. 2009-212301, it is proposed that isopropyl alcohol (IPA) is supplied to the front surface of the substrate while heating a substrate by supplying hot water to a rear surface of the substrate. IPA is a low surface tension liquid of which surface tension is lower than water. Water is thereby replaced by IPA and the IPA is thereafter eliminated from the substrate by spinning off the IPA by a centrifugal force.